Fiber board and process of making the same



Oct. 30, 1928. 1,689,812

F. WOOD FIBER BOARD AND PROCESS OF MAKING THE SAME Filed NOV. 17, 1926 Patented Oct. 30, 1928.

UNITED STATES PATENT OFFICE.

FREDERICK P. WOOD, OF ADRIAN, MICHIGAN, ASSIGNOR TO SIMPLEX PAPER CORPORA- TION, OF ADRIAN, MICHIGAN, A CORPORATION OF MICHIGAN.

FIBER BOARD AND PROCESS OF MAKING THE SAME.

Application filed November 17, 1926. Serial No. 148,798.

This invention relates to a multiple-ply fiber board such as may be used to advantage for panels, linings, backings, etc. In connection with the manufacture of bodies for automobiles, the present invention is particularly suitable, owing to its ability to meet certain very unusual and exacting conditions.

Accordingly, in the description to follow, the

fiber board of my invention will be considered with special reference to such use, although, of course, it may be employed otherwise, if desired.

To fulfill the requirements demanded by makers and users of automobiles, a board of the kind in question should be inexpensive, light in weight, moderately flexible so as to conform to body curvatures, sufficiently tough to afford reinforcement to its associated parts, immune from any appreciable expansion or contraction under changing conditions of temperature, and proof both against water and moisture. It should also lie flatwhen required so to do, and be free from warping or cockling. By the present invention, I am enabled to produce a board having these general characteristics together with certain other desirable properties to which attention will hereinafter be directed. Also the manufacture of such a board is accomplished by the employment of certain steps and measures which constitute a novel process. These several points will be explained more at length in the description and claims to follow, taken in connection with the accompanying drawing wherein my invention is set forth in the manner following:

Figure 1 which is a diagrammatic view pre sents a side elevation of an apparatus suitable for applying a water treatment to the paper which forms one of the inner plies of the board;

Fig. 2 is a similar view of an apparatus suitable for combining the'several paper plies into the fiber board; and

Fig. 3 is a fragmentary perspective view of a board as it appears when built up of three plies.

The present board may be advantageously.

produced from kraft paper made in accordance with any approved process.- Such a paper is characterized by fibers disposed generally in a single direction and constituting a definitely recognizable grain. The width of the paper sheet transversely of its grain is variable according to the moisture content within its fibers. By increasing the humidity five or six percent, by weight, an 86 roll of kraft paper will widen as much as a half or three quarters of an inch. This is due to a tendency on the part of the fibers to swell or expand transversely when subjected to humidity conditions above normal. A multiple-ply board which is built up from paper sheets having these characteristics is accordingly liable to develop a wave, warp, or cockle, particularly along the cross cu-tedges of its inner ply or plies. I account for this by the fact that the exposed ends of the fibers are unable to keep out the moisture which will penetrate for a distance of perhaps two inches. The result of this is a distortion, warping, or cockling of the board I in a direction transversely of its grain. According to the present invention, however, I seal a pretreated inner ply or plies between 7 outer plies of material which can be rendered roof both against moisture and water, therevy producing a fiber board which obviates this objectionable cockling tendency. The method pursued requires first of all an initial treatment of the paper forming the inner plies. This consists in pre-expanding the fibers in the sheets forming the inner plies preliminary to assembly between the outer plies of the board. As a convenient means ofeffecting this pre-expansion, I have shown in Fig. 1 an apparatus having a mounting for a paper roll A. The paper sheet unwound from this roll passes between idlers 4 and 5, thence over another idler 6, and ifdesired, between cutters 7 which sever the paper into desired widths. The paper sheet is then led onto a rewinding reel to be wound onto a roll B. Associated with this apparatus is a sprayer 8 with which is connected a valved supply pipe 9 leading from a tank 10 wherein I have shown a heating coil 11. The sprayer which may take the form of a pipe extending the width of the paper discharges thereupon a fine stream of water which is absorbed into its pulp to the limit of its capacity. With this water bath may be associated a deliquescent agent, such as glycerine, also a soap solution, both of which, however, are optional, the purpose of the former being to fix the expansion and of the latter to facihtate act-ion of the cutting dies when the board is to be severed. Any overflow from the spra er is drained into a pan 12. The result of t is sprayer treatment is to raise the moisture content to perhaps ten or eleven percent by weight, with'a consequent expansion of its fibers whereby the paper width is increased to a maximum point. The wet paper roll B is allowed to stand for perhaps two days during which time the pulp becomes thoroughly impregnated.

In this pre-expanded condition the paper is then ready for assembly with other sheets to form a board, some such machine as is suggested in Fig. 2, being used for this purpose. In this apparatus are employed upper and lower companion rollers 12 and 13, the latter of which dips into a pan 14 which may contain a liquefied binder such as asphaltum, and a second pair of compression rollers 15 and 16 between which the several plies are fed. The outer fiber sheets 0 and d are received into the machine from two rollers C and D. The paper sheet 0 is passed over an idler roller 17 and thence between the two pressure rollers 15 and 16. Likewise the pa er sheet (.Z is passed around the lower rol er 16 and thence between this roller and its companion roller 15. From the other roller B the pre-expauded sheet 7) is taken over an idler roller 18 which is located adjacent a second pan 19 from which a binder such as liquefied asphaltum may be thrown onto the upper side of the sheet prior to its assing between the two rollers 12 and 13.

his latter sheet I) then travels between the two rollers 15 and 16 and also between the other two sheets o and d. The inner paper sheet I) so coated with asphaltum on its upper side from the pan 19 is also coated similarly on its under side by contact with the dip roller 13, so that when brought into contact with the other two sheets by traveling through the compression roller 15 and 16, the three sheets are united to produce a multipleply product such as is shown in Fig. 3. From the compression rolls the product is taken around a pair of cooling drums 19 and 20 which so reduce the temperature of the asph altum that it is caused to set. The product may then pass onto a reel where it is wound into a roll 21 convenient for handling. The sheet is ordinarily cut in boards of a desired length, this operation taking place,

' by preference, after it is wound into a roll 21.

Athree-ply board produced in the manner described, is advantageous for most purposes. but may, if desired. be treated to a second operation which adds two additional plies.

As this involves merely a. duplication of the steps already described. and is already set forth in my co-pending application Serial No. 43,085. filed July 13. 1925. it is not deemed necessary here to go into a further explanation thereof.

A multiple-ply board so produced as the result of this second operation is shown in Fig. 3. It is characterized by intermediate layers of asphaltum, each designated as m, which, according to my invention, should be so treated as to render the product fit for the special conditions of its use. For this purpose I may combine with the asphaltum an oxidizable medium such as China wood oil, linseed oil, or'the like, the efiect of which is to prevent liquefaction at moderately high temperatures and crystallization at low temperatures. The use of some such stabilizing agent is desirable as the natural tendencies of the asphaltum are thereby modified to the extent that it is, for all practicable purposes, rendered immune to temperature conditions. I have ascertained that by treating -the asphaltum in this manner, the board will remain substantially unaffected even though it be subjected to temperature changes extending through a range of more than 250.

Experience has demonstrated that a multiple-ply fiber board produced as above described will remain flat irrespective of humidity conditions. It is thus rendered suitable for use as a panel board or for other purposes where freedom from cockling is highly desirable. It possesses a degree of toughness sufficient to appreciably reinforce an automobile body or other structure with which it is associated. It may be bent to a considerable extent without breaking, and be returned againto its original form without checking or creasing, this being possible because of the plastic character of the asphaltum which permits the several plies to slip upon each other under stress.

I claim:

1. A multiple-ply board consisting of a plurality of fibrous sheets each having a grain in parallelism, the fibers of the outer sheets being of normal size as contrasted with inboard, substantially as described.

2. A multiple-ply board in which is combined an inner fibrous sheet wherein the fibers are expanded, and outer sheets also of fibrous material united therewith to form a board, the fibers of the outer sheets being of normal size, substantially as described.

3. A multiple-ply board in which is a pair of outer sheets united by an adhesive with an inner sheet of fibrous material in which the fibers are in a fixed expanded condition, the several sheets constituting a'boar'd, substantially as described.

4. The process of making a multiple-ply board from fibrous sheets which consists in expanding the fibers of one sheet and thereafter in uniting therewith other sheets forming the outer plies. the fibers of the outer plies being non-expanded substantially as described.

The process of making a multiple-ply board from fibrous sheets having a grain, of

mean: 3

' I transversly expanding the fibers of one sheet, wherebfi the fibers are expanded, in combinand thereafter in adhering thereto other ing wit said water treatment a deliquescent sheets whose fibers are of normal size, subagent whereby to fix the expansion, and 10 stantially as described. thereafter in uniting to opposite faces of the 5 6. The process of making a multiple-ply sheet other sheets which form outer plies board from fibrous sheets which consists in of the board, substantially as described. subjecting one sheet to a water treatment FRED. P. WOOD. 

